Syria Conflict: Russia Must Act Now to End Bloodshed,

Russia is directly complicit in the bloodshed taking place in Syria and must act immediately to help bring an end to the countrys long-running conflict, the UK defence secretary, has said.

Russia must show the resolve necessary to bring this regime to heel, said Michael Fallon in remarks that came a day after Boris Johnson, the foreign secretary, cancelled a trip to Moscow after a chemical attack on civilians in Idlib province and the subsequent US missile strike against the Syrian regime.

The Russians have influence in the region, Fallon wrote in the Sunday Times. They helped broker the original deal to put chemical weapons out of commission. This latest war crime happened on their watch. In the past few years, they have had every opportunity to pull levers and stop the civil war.

Russia was the main backer of Syrias president, Bashar al-Assad, Fallon said, adding: By proxy Russia is responsible for every civilian death last week.

If Russia wants to be absolved of responsibility for future attacks, Vladimir Putin needs to enforce commitments, to dismantle Assads chemical weapons arsenal for good, and to get fully engaged with the UN peacekeeping progress.

Johnson had been scheduled to fly to Moscow on Monday for talks with Sergei Lavrov, his Russian counterpart. But the Foreign Office said the trip had been called off because developments in Syria had changed the situation fundamentally.

The international development secretary, Priti Patel said on Sunday the cancellation of the trip did not mean contact with Russia was being cut altogether.

We are constantly engaging with all our counterparts, and there has been dialogue, she told the Andrew Marr Show on BBC1. The foreign secretary has engaged with his Russian counterpart previously as well. These discussions are continuous, and that is the right approach.

However, Labours John McDonnell said he believed it was a mistake for Johnson to cancel the visit.

I think he should be there now, saying to the Russians just how appalling the situation is and the role that they should play, the shadow chancellor told Skys Sophy Ridge on Sunday. We should be frank with them and we shouldnt just allow the Americans to go off an do that we should be doing that ourselves.

The shadow foreign secretary, Emily Thornberry, said that while opinions inside the Labour party differed, she agreed with Jeremy Corbyn that the US missile strike was not the way forward.

There is no military solution to this, she told the Marr Show. The only one is a political one, and the question is, has the last week brought a political solution any closer. Im afraid it hasnt.

Nikki Haley, the US ambassador to the UN, said defeating Islamic State, pushing Iranian influence out of Syria and ousting the Syrian president were now priorities for Washington.

Michael Fallon with his US counterpart James Mattis. Photograph: Victoria Jones/PA

Theres not any sort of option where a political solution is going to happen with Assad at the head of the regime, she said in an interview on CNNs State of the Union, to be broadcast on Sunday.

Haley said defeating Isis was still the number one goal, but she added: If you look at his actions, if you look at the situation, its going to be hard to see a government thats peaceful and stable with Assad. Regime change is something that we think is going to happen.

He wrote: The Americans believed there were no peaceful means of stopping Assad using gas against his population. Given repeated Russian blocking in the UN security council, the US was determined to act.

By sending Tomahawk missiles to attack the airfield, aeroplanes and equipment believed to be involved, it has sent a strong signal to the Syrian regime to think twice before using gas in future.

Fallon said Theresa May was told before the strike took place, and that he and the US defence secretary, James Mattis, had been in touch to discuss the situation.

Falloon also argued for Assads departure, writing: Someone who uses barrel bombs and chemicals to kill his own people simply cannot be the future leader of Syria. Assad must go and the search for stability begin.